The present invention relates generally to police radar detectors used in motor vehicles and, more particularly, to police radar detectors that utilize a motor vehicle's position, velocity and/or heading to minimize false alarms.
Many operators of motor vehicles utilize radar detectors to alert them to he fact that their speed is being monitored by law enforcement agencies. However, conventional radar detectors often generate “false alarms.” These false alarms are annoying to the operators of motor vehicles. In fact, various automotive publications publish results of “false alarm” tests. Thus, anything that can be accomplished by the manufacturer to reduce the number of false alarms without reducing detection of police radar is commercially valuable.
In addition to police radar signals, there are many different sources of microwave signals in the frequency bands allocated to police radar by the U.S. Federal Communications Commission (FCC). For example, motion-detecting burglar alarms and automatic door openers also operate in the frequency band allocated to police radar. Thus, a need exists for a radar detector that can distinguish between signals generated by a police radar transmitter and those generated by other devices which utilize microwave signals within the same frequency bands.
Still another source of annoying false alarms occurs when an operator of a motor vehicle is travelling at a speed that is below the legal speed limit, such as occurs when the operator is in traffic, and the radar detector alerts him to an incoming radar signal. Even if a police radar signal is monitoring the speed of the operator's vehicle, because the velocity of the vehicle is below the legal speed limit, the operator of the vehicle may not need to be alerted to the presence of the police radar signal. Thus, a need exists for a radar detector that does not generate an alert if the velocity of the radar detector is below the legal speed limit.
Operators have become accustomed to radar detectors activating in certain locations along commonly traveled streets and highways. Police radar units may be deployed by the side of the roadway at these locations since the police also are aware of the local activation signals and the police are aware that the signals tend to mask their own speed monitoring radar units. Thus, a need exits for a radar detector that can avoid generating a false alarm due to such accustomed radar signals while still generating an alert for such police radar signals.